Steam Sterilizer System

Abstract

1. A steam sterilizer system comprising: a sterilizer chamber configured to receive an item to be sterilized; a steam generator configured to convert liquid water into steam to be supplied to the sterilizer chamber, the steam generator including a heat exchanger; and steam recycling equipment configured to receive residual steam present in the sterilizer chamber after a steam treatment step, the steam recycling equipment configured to pass residual steam from the sterilizer chamber through the heat exchanger as a heat transfer medium, and to transfer heat from the residual steam to liquid water in the steam generator, the steam recycling equipment including a compressor configured to receive residual steam from the sterilizer chamber and compress the received residual steam to a higher pressure, after which the steam recycling equipment passes the compressed residual steam to the heat exchanger.

Description

[Technical Field]

[0001] The present disclosure relates to steam sterilizer systems that can be used, for example, in a hospital's central sterile services department (CSSD) to process used medical supplies. [Background technology]

[0002] Microbial inactivation by steam sterilization involves the presence of steam (moist heat) and high temperatures for a specific period of time. During such steam sterilization processes, the material to be sterilized must be in contact with the steam and its condensate for that period of time. Steam sterilization processes typically involve several different processing steps and may include several discharges. In current systems, such discharges purge the residual steam into a sewer system. Such discharges waste a large amount of energy because the residual steam still contains a lot of energy. However, recovering the residual steam to avoid wasting energy is difficult because, even if the residual steam is hot, it is not hot enough for additional steam sterilization. An additional consideration in the discharge of residual steam is the substantial amount of water required to cool the residual steam to protect the vacuum system and to allow its release into the sewer system. It would also be desirable to reduce such water consumption. Summary of the Invention [Problem to be solved by the invention]

[0003] It is an object of the present disclosure to present a steam sterilizer system that at least partially alleviates the efficiency drawbacks of the prior art. This object and other objects, which will become apparent hereinafter, are achieved by the steam sterilizer system as defined by claim 1. Some non-limiting exemplary embodiments are presented in the dependent claims. [Means for solving the problem]

[0004] Applicant has determined that the residual steam should be passed from the sterilizer chamber through a compressor that compresses the received residual steam to a higher pressure, thereby increasing the temperature of the residual steam and allowing the energy of the residual steam to be recovered, which also reduces the water consumption associated with draining the residual steam to a sewer system.

[0005] Thus, in accordance with at least a first aspect of the inventive concept, there is provided a steam sterilizer system comprising: - a sterilizer chamber configured to receive articles, such as medical supplies, to be sterilized in a sterilization process in the sterilizer chamber; a steam generator configured to receive liquid water and convert the liquid water into steam for delivery to a sterilizer chamber, the steam generator including a heat exchanger; - a steam recycling facility configured to receive at least a portion of residual steam present in a sterilizer chamber after a steam treatment stage of a sterilization process, and configured to pass residual steam from the sterilizer chamber through said heat exchanger as a heat transfer medium, to transfer heat from the residual steam to liquid water in a steam generator; and Including, A steam sterilizer system is provided in which the steam recycling facility includes a compressor configured to receive residual steam from the sterilizer chamber and compress the received residual steam to a higher pressure, after which the steam recycling facility passes the compressed residual steam to the heat exchanger.

[0006] Compressing the residual steam to a higher pressure and thereby to a higher temperature requires less energy than would be required to achieve the same temperature by other conventional heating means. The thermal energy of the compressed residual steam can then be effectively used as a heat transfer medium to heat the fresh water in the steam generator. This has an additional benefit: any contaminants, debris, or other undesirable particles that may accompany the residual steam from the sterilizer chamber will not be recirculated into the sterilizer chamber because the residual steam will simply be used as a heat transfer medium, allowing steam to be generated from the fresh water in the steam generator.

[0007] Moreover, because the compressed residual steam is used as a heat transfer medium in the heat exchanger, it is effectively cooled as heat is transferred to the fresh water in the steam generator. The compressed residual steam that passes through the heat exchanger will have a lower temperature and can form condensate, which can be discharged to the sewerage system with less or no water cooling. Thus, the steam sterilizer system of the present disclosure can avoid wasting the considerable amount of water that is traditionally used to cool the residual steam discharged from the sterilizer chamber before it is released into the sewerage system. Moreover, it may be considered to recover the condensate or any remaining residual steam that has passed through the heat exchanger instead of discharging it to the sewerage system.

[0008] Different sterilization processes can include different numbers and types of steam treatment stages. For example, a sterilization process can begin with a subatmospheric pretreatment to remove air by vacuum, followed by steam injection, both of which can be repeated multiple times to generate a diluted atmosphere containing primarily air-free steam. The first subatmospheric stage can be followed by a superatmospheric pretreatment through steam injection to higher pressures, followed by evacuation to near-atmospheric pressure, which is repeated to heat the load and further remove residual air and accumulated non-condensable gases (NCGs). The third stage of pretreatment can include controlled heating to adjust the steam to the sterilization temperature. Sterilization is then achieved by holding a constant temperature for a specified time. Sterilization can then be followed by a posttreatment involving, for example, vacuum drying. Some stages may be more suitable for residual steam recovery than others. The steam exhausted from subatmospheric pretreatment may be more or less contaminated with air and cooler / leaner than that later in the process. Therefore, later stages may be more advantageous for residual steam recovery. Furthermore, in later stages, the residual steam pressure will be higher than that in the initial subatmospheric pretreatment stage. Therefore, later stages require lower compression ratios than earlier stages. Residual steam from superatmospheric pretreatment and from portions of posttreatment is relatively low in air or NCG and is extremely hot and dense, making it particularly suitable for recovery during compression with reasonable compression ratios. Nevertheless, it should be understood that the steam sterilizer system of the present disclosure is not limited to recovering residual steam from steam treatment stages later in the sterilization process. It is also possible for the steam sterilizer system to be operated to recover residual steam during discharge earlier than pretreatment. In some preferred embodiments, residual steam is recovered from a steam sterilization stage performed at superatmospheric (high pressure) and / or high temperature conditions.

[0009] According to at least one exemplary embodiment, the steam recycling facility includes an intermediate steam storage, into which the compressed residual steam is guided before passing to the heat exchanger, the pressure in the intermediate steam storage preferably being higher than the pressure in the steam generator, and the intermediate steam storage including, inter alia, a pressure vessel. Having a higher pressure in the intermediate steam storage compared to the pressure in the steam generator improves heat transfer. By way of purely illustrative example, the pressure in the intermediate steam storage can be, for example, 500-900 kPa, while the pressure in the steam generator can be, for example, 360-410 kPa. It should also be understood that, during operation, the pressure in the intermediate steam storage is preferably higher than the pressure in the sterilizer chamber.

[0010] From the above, it can be seen that according to at least one exemplary embodiment, a compressor is positioned in the fluid path between the sterilizer chamber and the intermediate steam storage to compress residual steam from the sterilizer chamber before it enters the intermediate steam storage.

[0011] Since not all the energy can be recovered from the residual steam, the intermediate steam store can be provided with its own heating facility, such as one or more electric heaters. Moreover, such heating facility can be useful during start-up of the intermediate steam store from a cold state, before sufficient hot steam is available for recovery.

[0012] The intermediate steam storage may potentially receive superheated steam from the compressor, in which case it may be appropriate to reduce the temperature to avoid excessive heat. Superheated steam results in insufficient heat transfer in the heat exchangers of the steam generator. Therefore, it may be advantageous to control superheat before it reaches the heat exchangers. Also, limiting superheat before or during the compression stage can protect the compressor from excessive temperatures. However, limiting superheat downstream of the compressor is also conceivable. Therefore, it should be understood that there are several possible strategies for controlling superheat. Some examples will be discussed in relation to the exemplary embodiments below.

[0013] According to at least one exemplary embodiment, the intermediate steam storage has an inlet at the bottom of the intermediate steam storage, through which compressed residual steam can be received, thereby allowing the residual steam to rise through the water contained in the intermediate steam storage. The presence of water in the intermediate steam storage buffers the residual steam, countering superheating and allowing the residual steam to return to saturation. A steam saturation table can be used to control the temperature based on the pressure in the intermediate steam storage. Thus, the intermediate steam storage can be suitably provided with various sensing devices, such as pressure and / or temperature sensors. The intermediate steam storage can typically suitably contain both water and steam during normal operation. The water has a buffering effect on the residual steam and can also be used to generate new steam (e.g., by an electric heater or another heating facility) when the system starts up. After start-up, the water can also be used to add new steam to compensate for losses.

[0014] According to at least one exemplary embodiment, the intermediate steam reservoir includes a screen with a plurality of holes for diffusing the transport of steam bubbles through the water volume in the intermediate steam reservoir, with the steam bubbles rising to an upper steam volume above the surface of the water volume. By distributing the remaining steam over a larger surface, overheating can be reduced or controlled.

[0015] Instead of or in addition to integrating superheat control into the intermediate steam store as exemplified above, the steam recycling facility can be provided with any other suitable cooling device, which is at least partly reflected in the following exemplary embodiments.

[0016] In general terms, according to at least one exemplary embodiment, the steam recycling facility may include a cooling device configured to reduce the temperature of the superheated residual steam to saturated residual steam, and in particular the cooling device is disposed along the fluid path between the sterilizer chamber and the intermediate steam storage.

[0017] According to at least one exemplary embodiment, the cooling device is configured to spray water into the compressor. This can be beneficial because the compressor's materials can be better protected from overheated residual steam. The cooling device can include, for example, a nozzle, and water can be sprayed into the residual steam flow by the nozzle and with assistance from a feedwater pump. The water can be sprayed into the decreasing compression volume of the compressor during the stroke, causing evaporation and instant cooling as soon as overheating occurs. This can be coordinated to start at a specific spot along one revolution of the compression stroke, for example, by reading a position sensor that can be provided on the compressor. The duration can then be controlled by a controller, and the saturation temperature can be reached without entering a wet zone, for example, using feedback from temperature and pressure sensors to calculate the saturation temperature. However, it is also conceivable to spray water without coordinating the injection with the compression stroke.

[0018] According to at least one exemplary embodiment, the cooling device may be in the form of an injector configured to spray water onto the superheated residual steam upstream or downstream of the compressor. A location downstream of the compressor does not provide high temperature protection for the compressor's internal components as a location upstream of the compressor or directly into the compression stroke, but may be more convenient from an assembly standpoint. The location downstream of the compressor may be in the piping or even directly into the intermediate steam storage. According to at least one exemplary embodiment, the cooling device may be in the form of a heat exchange device provided between the compressor and the intermediate steam storage.

[0019] According to at least one exemplary embodiment, the steam sterilizer system further includes a control unit configured to determine when the steam treatment stage of the sterilization process is complete and, based on such determination, control a valve positioned upstream of the compressor to allow residual steam to pass from the sterilizer chamber to the compressor. Technical advantages can include the control unit being programmable to open the valve during those stages of the sterilization process that would allow the compressor to operate at a reasonable compression ratio to achieve a desired pressure and temperature for the received residual steam. The control unit can also be used to control the operation of other parts of the steam sterilizer system.

[0020] The control unit may include a microprocessor, microcontroller, programmable digital signal processor, or another programmable device. The control unit may also or instead include an application-specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. If it includes a programmable device such as the above-mentioned microprocessor, microcontroller, or programmable digital signal processor, the processor may further include computer-executable code that controls the operation of the programmable device. The control unit is preferably configured for use with a steam sterilizer system and is provided with electronic instructions for implementing and controlling any of the operational steps described herein. The control unit may include any electronics and instructions for controlling the processes described herein.

[0021] According to at least one exemplary embodiment, the intermediate steam storage is a first intermediate steam storage, and the steam recycling facility includes a second intermediate steam storage, to which the compressed residual steam can be guided before passing to the heat exchanger. The second intermediate steam storage can have a lower pressure than the first intermediate steam storage. For example, the second intermediate steam storage can have a pressure in the range of 150 to 300 kPa. The second intermediate steam storage can be used to compress steam maintained in a saturated equilibrium state with water, and it can be used to preheat feedwater in an economizer, or its contents can be used for a second compression stage from the lower steam pressure in the second intermediate steam storage to the higher pressure in the first intermediate steam storage. Having two intermediate steam storages can save more energy because the compression ratio is also lower, allowing for a much lower minimum possible pressure for the discharge of the sterilizer chamber. The same compressor can be used appropriately for different modes of operation, and flow can be directed by controlling different valves in the piping between the sterilizer chamber, the first intermediate steam reservoir, and the second intermediate steam reservoir.

[0022] According to at least one exemplary embodiment, the control unit is configured to operate the steam recycling facility in a first storage mode of operation by controlling compressed residual steam to be provided initially to the first intermediate steam storage until the pressure inside the sterilizer chamber drops below a predefined pressure level. Providing compressed residual steam to the first intermediate steam storage is advantageous when the pressure inside the sterilizer chamber is high because the compression ratio is relatively low. However, when the pressure inside the sterilizer chamber drops, the compression ratio becomes too large after a while to efficiently continue this first storage mode of operation. Therefore, the control unit can switch the compressed residual steam to be provided to the second intermediate steam storage.

[0023] Thus, according to at least one exemplary embodiment, the control unit is configured to operate the steam recycling facility in a second storage operating mode by controlling compressed residual steam to be provided to a second intermediate steam store instead of to the first intermediate steam store when the pressure inside the sterilizer chamber drops below said predefined pressure level, which is advantageous as the second intermediate steam store provides a lower counter-pressure.

[0024] According to at least one exemplary embodiment, the control unit is configured to operate the steam recycling facility in an inter-storage operating mode by controlling the transfer of compressed residual steam stored in the second intermediate steam storage to the first intermediate steam storage via a compressor, thereby further increasing the pressure of the residual steam exiting the second intermediate steam storage. This can be the same compressor positioned in the path between the sterilizer chamber and the first intermediate steam storage, or it can be a separate compressor in the fluid path between the first intermediate steam storage and the second intermediate steam storage. This is advantageous because this inter-storage operating mode can increase the pressure and energy in the first intermediate steam storage for subsequent heat transfer in the steam generator. However, it should be noted that using energy from the second intermediate steam storage for direct heating is also conceivable.

[0025] According to at least one exemplary embodiment, the steam recycling facility includes a plurality of controllable valves for controlling the flow of steam to and from the first intermediate steam storage and the second intermediate steam storage, and a control unit configured to control the controllable valves to switch between the different operating modes. By using multiple controllable valves, it is possible, in some embodiments, to use only one compressor for all three operating modes.

[0026] According to at least one exemplary embodiment, the sterilizer chamber is a first sterilizer chamber, the steam generator is a first steam generator, and the steam sterilizer system comprises: - a second sterilizer chamber configured to receive items, such as medical supplies, to be sterilized; a second steam generator configured to receive liquid water and convert the liquid water into steam for delivery to a second sterilizer chamber, the second steam generator including a heat exchanger; and further comprising The steam recycling facility is also configured to guide the residual steam as a heat transfer medium through the heat exchanger of the second steam generator, transferring heat from the residual steam to the liquid water in the second steam generator. Thus, the steam sterilizer system is not limited to one sterilizer chamber, but can advantageously include one or more additional sterilizer chambers. A compressor can advantageously be used to provide compressed residual steam received from the first sterilizer chamber to the heat generator of either the first steam generator or the second steam generator. Similarly, in at least some exemplary embodiments, residual steam from the second steam sterilizer can be received by the compressor and then transferred to the heat exchanger of either the first or second steam generator. A common intermediate steam storage can be suitably provided, and the compressed residual steam is passed to the common intermediate steam storage before being transferred to one of the steam generators. In other exemplary embodiments, individual intermediate steam storages can be provided.

[0027] According to at least one exemplary embodiment, the steam recycling facility further includes a bypass line extending from a location downstream of the compressor but upstream of the steam generator, the bypass line being selectively controllable to allow compressed residual steam to bypass the steam generator and be returned to the sterilizer chamber. Such exemplary embodiments may or may not include the provision of one or more intermediate steam stores (such as those discussed above). In embodiments including intermediate steam stores, the bypass line can extend either upstream or downstream of the intermediate steam store. In either case, the advantage of having a bypass line is that there are no conversion losses (as compared to heat transfer in a heat exchanger within the steam generator).

[0028] The use of a bypass line can likewise be thought of as representing a second general aspect of the present disclosure.

[0029] Thus, in accordance with at least a second aspect of the general inventive concept, there is provided a steam sterilizer system comprising: - a sterilizer chamber configured to receive articles, such as medical supplies, to be sterilized in a sterilization process in the sterilizer chamber; a steam generator configured to receive liquid water and convert the liquid water into steam to be supplied to the sterilizer chamber; - a steam recycling facility configured to receive at least a portion of the residual steam present in the sterilizer chamber after a steam treatment stage of the sterilization process; and Including, the steam recycling facility includes a compressor configured to receive residual steam from the sterilizer chamber and compress the received residual steam to a higher pressure; A steam sterilizer system is provided in which the steam recycling facility further includes a bypass line extending from a location downstream of the compressor but upstream of the steam generator, the bypass line being selectively controllable to allow compressed residual steam to bypass the steam generator and be returned to the sterilizer chamber.

[0030] Therefore, unlike the first embodiment, this second embodiment does not require the compressed residual steam to be used as a heat transfer medium in the steam generator heat exchanger. Therefore, because no heat transfer is performed in this second embodiment, there are no conversion losses; rather, the compressed residual steam can be reused as a sterilization medium in the sterilizer chamber. To reduce the risk of unwanted material re-entering the sterilizer chamber, the steam sterilizer system can appropriately recover residual steam from later stages of the sterilization process.

[0031] In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art unless expressly defined otherwise herein. All references to "elements, arrangements, components, means, steps, etc." should be broadly interpreted as referring to at least one instance of an element, arrangement, component, means, step, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated otherwise. Further features of and advantages associated with the inventive concepts will become apparent upon review of the appended claims and the following description. Those skilled in the art will recognize that different features of the inventive concepts can be combined to produce embodiments other than those described below without departing from the scope of the inventive concepts. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a schematic diagram of a steam sterilizer system according to at least one exemplary embodiment of the present disclosure having one intermediate steam reservoir. [Figure 2] FIG. 10 is a schematic diagram of a steam sterilizer system in accordance with at least another exemplary embodiment of the present disclosure having two intermediate steam reservoirs. [Figure 3] FIG. 1 illustrates an example of a steam sterilizer that may be used with the disclosed system. [Figure 4] FIG. 1 illustrates an example of a steam generator that may be used with the disclosed system. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the system are shown. The system may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein. Rather, the embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the scope of the system to those skilled in the art. It should therefore be understood that the present disclosure is not limited to the embodiments described herein and illustrated in the drawings. Rather, those skilled in the art will recognize that many changes and modifications may be made within the scope of the appended claims. Like reference numerals refer to like elements throughout the description.

[0034] FIG. 1 is a schematic diagram of a steam sterilizer system 1 according to at least one exemplary embodiment of the present disclosure. At a general level, the steam sterilizer system includes a container 2 for water, a steam generator 4, and a sterilizer chamber 6. Fresh or recycled liquid water can be supplied to the container 2. Water from the container 2 can be delivered to the steam generator 4. The steam generator 4 includes a heat exchanger 8 configured to receive a heat transfer medium for transferring heat to the liquid water in the steam generator 4, thereby converting the liquid water into steam. The steam is then passed from the steam generator 4 to the sterilizer chamber 6. Inside the sterilizer chamber 6, items to be sterilized (e.g., medical supplies, etc.) can be exposed to steam generated by the steam generator 4.

[0035] Articles received into the sterilizer chamber 6 are sterilized in a sterilization process. Such a sterilization process may include multiple different steam treatment stages. During such steam treatment stages, steam may be repeatedly delivered from the steam generator 4 to the sterilizer chamber 6. As previously explained in this disclosure, traditionally, after completion of a steam treatment stage, the residual steam has been drained to a sewerage system 10. This is not only a waste of thermal energy (considering the heat of the steam), but also a waste of water (water is required to cool the residual steam before it can be drained to the sewerage system). Therefore, according to the general inventive concept, the steam sterilizer system is provided with a steam recycling facility 12.

[0036] The steam recycle facility 12 is configured to receive at least a portion of the residual steam present in the sterilizer chamber 6 after the steam treatment stage of the sterilization process. As previously explained, recovery of the residual steam may be particularly advantageous after later steam treatment stages, but may also be considered after completion of earlier steam treatment stages. The steam recycle facility 12 is configured to pass the residual steam from the sterilizer chamber 6 through the heat exchanger 8 as a heat transfer medium, which transfers heat from the residual steam to the liquid water in the steam generator 4.

[0037] The steam recycle facility 12 includes a compressor 14 configured to receive residual steam from the sterilizer chamber 6 and compress the received residual steam to a higher pressure before the steam recycle facility 12 passes the compressed residual steam to the heat exchanger 8.

[0038] The steam recycle facility 12 may also include an intermediate steam storage 16, which is positioned between the compressor 14 and the steam generator 4. The compressor 14 may therefore be positioned in the fluid path between the sterilizer chamber 6 and the intermediate steam storage 16 to compress residual steam from the sterilizer chamber 6 before the residual steam enters the intermediate steam storage 16. The function of the intermediate steam storage 16 will be discussed in more detail further in this disclosure.

[0039] The steam sterilizer system 1 may include a control unit 18 configured to communicate with various components of the steam sterilizer system 1 and to control the operation of certain components and receive input signals from the various components. The control unit 18 may be configured to communicate, send / receive, etc., instructions wirelessly or via wires. The control unit 18 may include electronics, a processor, memory, electronic instructions, and other elements useful for controlling the systems described in this disclosure (including any embodiment thereof). The control unit 18 may control various valves of the steam sterilizer system 1 to control the flow of fluids, such as water, steam, etc., through different passageways. For example, the passageway 20 from the sterilizer chamber 6 to the compressor 14 may be provided with a valve 22 controllable by the control unit 18. The valve 22 may be, for example, a proportional valve. The control unit 18 may close the valve 22 when residual steam from the sterilizer chamber 6 should not be collected and open the valve 22 when residual steam should be collected. Thus, the control unit 18 can be configured to determine that the steam treatment stage of the sterilization process is complete and, based on such determination, control the valve 22 positioned upstream of the compressor 14 to allow residual steam to pass from the sterilizer chamber 6 to the compressor 14.

[0040] The compressor 14 increases the pressure of the residual steam, thereby increasing its temperature. There is a possibility that the residual steam may become superheated. Therefore, it may be desirable to control (e.g., cool) any superheated residual steam, as superheated steam results in insufficient heat transfer in the heat exchanger 8. Therefore, it may be desirable to convert the superheated steam to saturated steam. To this end, the steam recycling facility 12 may include cooling devices 24a, 24b, 24c, and 24d. The cooling devices may be provided to reduce the temperature of the superheated residual steam to saturated residual steam. The cooling devices may be appropriately positioned along the fluid path between the sterilizer chamber 6 and the intermediate steam storage 16. Three different exemplary locations for spray-injecting water into the superheated residual steam are illustrated in FIG. 1 . One of these three different options will usually be sufficient to achieve saturated residual steam. Three illustrated options are injection upstream of the compressor 14 (24a), injection directly into the compressor 14 (24b), and injection downstream of the compressor 14 (24c). A further option or supplement is the use of a cooling device in the form of a heat exchange device 24d, which is shown here downstream of the compressor 14. Each one of the illustrated cooling devices 24a-24d, i.e., spray injectors 24a, 24b, 24c and heat exchange device 24d, is shown as being positionable upstream of the intermediate steam storage 16. The steam sterilizer system 1 can include sensing devices 26, such as one or more temperature sensors and one or more pressure sensors. Based on input from such sensing devices 26, the control unit 18 can calculate the saturation temperature and, therefore, determine the appropriate duration for cooling by the cooling devices 24a-24d to reach the saturation temperature without entering a wet zone.

[0041] The intermediate steam storage 16 can also function to control superheat. The compressed residual steam can be guided to the intermediate steam storage 16 before it is passed to the heat exchanger 8 of the steam generator 4. By having a higher pressure in the intermediate steam storage 16 compared to the pressure in the steam generator 4, improved heat transfer is achieved through the heat exchanger 8. The intermediate steam storage 16 preferably includes a pressure vessel. The pressure vessel can be provided with liquid water 28, which can serve two purposes: one is superheat control and the other is the generation of additional steam. With regard to superheat control, the intermediate steam storage 16 can be provided with an inlet 30, which can be at the bottom of the intermediate steam storage 16. The compressed residual steam can be received through the inlet 30, thereby allowing the residual steam to rise through the water 28 contained in the intermediate steam storage 16. Excess heat can thereby be transferred into the water 28. The intermediate steam storage 16 can suitably include a screen 32 with a plurality of holes for diffusing the transport of steam bubbles 34 through the water volume 28 in the intermediate steam storage 16. The steam bubbles 34 rise to an upper steam volume 36 above the surface of the water volume 28, and the temperature of the steam is reduced as the steam rises through the water 28. Regarding the generation of additional steam, this may be relevant when starting up the system. Therefore, the intermediate steam storage 16 may be equipped with an electric heater 38 or some other heating facility. However, even when the system is running, the water 28 can be used to add new steam to compensate for losses. The liquid water 28 in the intermediate steam storage can be delivered from the container 2, for example, via an economizer 40 for preheating the supplied water. The control unit 18 can control valves 42, 44 to control the water to be delivered from the container 2 to the steam generator 4 and / or the intermediate steam storage 16.

[0042] The saturated residual steam can exit the intermediate steam storage 16 through an outlet 46 provided at the top of the intermediate steam storage 16. A passage 48 from the outlet 46 guides the compressed saturated residual steam to the heat exchanger 8 of the steam generator 4. After passing through the heat exchanger 8, the residual steam has transferred heat to the water inside the steam generator 4, thus lowering its temperature, and can be discharged from the heat exchanger 8 in the form of condensate in a drain 50. The passage 48 interconnecting the intermediate steam storage 16 with the heat exchanger 8 of the steam generator 4 can be suitably provided with a valve 52 controllable by the control unit 18. Thus, the valve 52 can be closed when not heating the water in the steam generator 4 and opened when heating the water in the steam generator 4.

[0043] Although only a heat exchanger 8 for receiving residual steam is shown in the steam generator 4, it should be understood that it would be useful to have additional heating elements to convert the water in the steam generator 4 to steam.

[0044] As shown schematically in the passage 48 between the intermediate steam storage 16 and the heat exchanger 8, a bypass line 54 (schematically indicated by an arrow) may be provided which is selectively controllable (e.g., by a valve controllable by the control unit 18) to allow the compressed residual steam to bypass the steam generator 4 and be returned to the sterilizer chamber 6. Although the bypass line 54 is shown as branching off from the passage 48 between the intermediate steam storage 16 and the heat exchanger 8, any other suitable location upstream of the compressor 14 but downstream of the steam generator 4 could be envisioned. Regardless of the location of the bypass line, it should be understood that the bypass line does not necessarily have to return the residual steam directly to the sterilizer chamber, but could also direct the residual steam to storage for later use.

[0045] The compressor 14 can be used to recover residual steam from additional sterilizer chambers. Thus, the steam sterilizer system 1 can include more than the sterilizer chambers 6 shown in FIG. 1. For example, at a branch 56 extending from the passageway 20 between the sterilizer chamber 6 and the compressor 14, and beside a valve 58 in that branch 56, another sterilizer chamber can be provided on the other side of that valve 58. Thus, the illustrated sterilizer chamber 6 can be referred to as the first sterilizer chamber, and the other sterilizer chamber on the other side of the valve 58 can be referred to as the second sterilizer chamber. Of course, more than two sterilizer chambers can be included in the steam sterilizer system 1 of the present disclosure, and steam can be recycled from each in a similar manner.

[0046] Similarly, at the branch 60 and valve 62 in the passage 48 between the intermediate steam store 16 and the heat exchanger 8, another steam generator can be provided on the other side of the valve 62. Such an additional steam generator can include its own heat exchanger to which the residual steam can be guided. The illustrated steam generator 4 can be referred to as the first steam generator, and the other steam generator on the other side of the valve 62 can be referred to as the second steam generator. Of course, more than two steam generators can be included in the steam sterilizer system 1 of the present disclosure.

[0047] The control unit 18 can be configured to control the operation of the different valves and the recovery of residual steam in an effective manner. Suitably, the timing of the sterilization processes in the different sterilizer chambers can be appropriately adjusted so that when the steam treatment step in one of the sterilizer chambers is completed, the steam treatment step in the other sterilizer chamber is being performed or is about to be performed. In this manner, the control unit 18 can alternately control the valves associated with the first and second sterilizer chambers. For example, the control unit 18 can control the valve 22 associated with the first sterilizer chamber 6 to be opened for the recovery of residual steam while the valve 58 associated with the second sterilizer chamber remains closed. Then, at a later point in time, the control unit 18 can instead control the valve 58 associated with the second sterilizer chamber 6 to be opened for the recovery of residual steam while the valve 22 associated with the first sterilizer chamber 6 remains closed. Similarly, the control unit 18 can alternately control the valve 52 associated with the first steam generator 4 to be opened, while the valve 62 associated with the second steam generator remains closed, and then vice versa. A further example is for the control unit 18 to control both valves 22 and 58 to be open in order to simultaneously withdraw residual steam from the first sterilizer chamber 6 and the second sterilizer chamber.

[0048] Turning now to FIG. 2, FIG. 2 is a schematic diagram of a steam sterilizer system 100 in accordance with at least another exemplary embodiment of the present disclosure. Many of the parts of the steam sterilizer system 100 in FIG. 2 may be the same as those illustrated for the steam sterilizer system 1 in FIG. 1. Thus, similar to FIG. 1, the steam sterilizer system 100 in FIG. 2 includes a container 2 from which water may be supplied to a steam generator 4, where the water is converted to steam and delivered to a sterilizer chamber 6. The residual steam may be received by a recycling facility 12. The recycling facility 12 includes a compressor 14 that increases the pressure of the residual steam received from the sterilizer chamber 6, and the compressed residual steam may be passed to and through a heat exchanger 8 of the steam generator 4, where it serves as a heat transfer medium for heating the water in the steam generator 4.

[0049] The steam sterilizer system 100 in Figure 2 includes an intermediate steam storage 16. Similar to the steam sterilizer system 1 of Figure 1, in the steam sterilizer system 100 of Figure 2, compressed residual steam can pass from the compressor 14, through the intermediate steam storage 16, and then to the heat exchanger 8 of the steam generator 4. Although the inlet is shown at the top of the intermediate steam storage 16 (to maintain clarity of the drawing), it should be understood that in practice the inlet can be suitably located at the bottom of the intermediate steam storage 16, allowing the residual steam to rise through the screen 32 and the water 28 in the intermediate steam storage 16, corresponding to what has already been discussed in relation to Figure 1.

[0050] The intermediate steam storage 16 in Figure 2 can be referred to as the first intermediate steam storage 16. The steam sterilizer system 100 in Figure 2 can further include a second intermediate steam storage 116, to which the compressed residual steam can be guided before the compressed residual steam is passed to the heat exchanger 8. The second intermediate steam storage 116 can be structurally similar to the first intermediate steam storage 16 and can include, for example, a screen 132 and water 128 through which the residual steam can rise.

[0051] The second intermediate steam storage 116 can have a pressure of, for example, 150-300 kPa. The second intermediate steam storage 116 can be used to compress steam maintained in saturated equilibrium with water, which can then be used to preheat feedwater in an economizer, or for a second compression stage from the lower steam pressure of 150-300 kPa in the second intermediate steam storage 116 to the first intermediate steam storage 16 (which can have a higher steam pressure of, for example, 500-900 kPa). Having two intermediate steam storages 16, 116 can save more energy because the compression ratio is also lower, and the lowest possible pressure for the discharge of the sterilizer chamber 6 can be much lower. The same compressor 14 can be used for different operating modes, and flow can be directed between different vessels by different valves and piping depending on priority and availability.

[0052] The control unit 18 can be configured to operate the steam recycling facility 12 in a first storage mode of operation by controlling compressed residual steam to be provided initially to the first intermediate steam storage 16 until the pressure inside the sterilizer chamber 6 drops below a predefined pressure level. Thus, the first storage mode of operation for steam conservation from higher pressures can be a controlled flow from the sterilizer chamber 6 through the compressor 14, via valve 22, and through the open valve 121 to the first intermediate steam storage 16. In this first storage mode of operation, valves 123 and 125 remain closed. When the pressure inside the sterilizer chamber 6 drops, the compression ratio will, after a while, become too large to effectively continue the first storage mode of operation. The control unit 18 can then operate the steam recycling facility 12 in a second storage mode of operation when the pressure inside the sterilizer chamber 6 drops below a predefined pressure level. The control unit 18 controls the compressed residual steam to be provided to the second intermediate steam storage 116 instead of to the first intermediate steam storage 16. Thus, the second storage operating mode then targets the second intermediate steam storage 116 instead, which has its lower counter pressure. In the second storage operating mode, valve 121 is closed and valve 123 is open. Valve 125 remains closed. The control unit 18 is also configured to operate the steam recycling facility 12 in a third operating mode, which may be referred to as an inter-storage operating mode. In the inter-storage operating mode, the control unit 18 controls the compressed residual steam stored in the second intermediate steam storage 116 to be transferred to the first intermediate steam storage 116 via the compressor 14, further increasing the pressure of the residual steam exiting the second intermediate steam storage 116. This may be the same compressor 14 located between the sterilizer chamber and the first intermediate vapor store 16, or it may be a different compressor.This is enabled when both valves 22 and 123 are closed, with valves 121 and 125 open. The inter-storage mode of operation results in increasing the pressure and energy in first intermediate steam store 116 for use in steam generator 4. It should be understood that it is also possible to use energy directly from second intermediate steam store 116 for heating.

[0053] Similar to the steam sterilizer system 1 of FIG. 1, the steam sterilizer system 100 of FIG. 2 may include one or more additional sterilizer chambers and one or more additional steam generators.

[0054] FIG. 3 illustrates an example of a steam sterilizer 200 that may be used with the system of the present disclosure (including any exemplary embodiment thereof) (e.g., with any one of sterilizer systems 1 and 100 in FIGS. 1 and 2, respectively). The steam sterilizer 200 includes a sterilizer chamber 202, which may correspond to, for example, sterilizer chamber 6 in FIGS. 1 and 2. The sterilizer chamber 202 is closed by a door 204 during the sterilization process, which may be opened to load non-sterilized articles into the sterilizer chamber 202 or to unload sterilized articles from the sterilizer chamber 202. In some exemplary embodiments, the steam sterilizer 200 may have another door on the opposite side of the sterilizer chamber 202, with loading occurring on one side of the sterilizer chamber 202 and unloading occurring on the other side. The steam sterilizer 200 may have an operation panel 206 that allows an operator to select the appropriate sterilization process for the articles to be sterilized. The steam sterilizer 200 may include a steam generator 208, such as the steam generator 4 in FIGS. 1 and 2. Thus, the steam sterilizer 200 in FIG. 3 may include a steam generator 4 and a sterilizer chamber 6 similar to those illustrated in FIGS. 1 and 2. At the bottom of the steam sterilizer 200, a drain 210 is provided for draining condensed steam and / or other fluids from the steam sterilizer 200. This drain 210 is typically different and separate from the port (shown in FIGS. 1 and 2) for steam exiting the sterilizer chamber 6 through valve 22 to the compressor 14 (which cannot be seen in this view). A water supply tank 212 is installed at the top of the steam sterilizer 200, and a header tank 214 for cooling water may also be installed.

[0055] FIG. 4 illustrates an example of a steam generator 300 that may be used with the system of the present disclosure (including any exemplary embodiment thereof) (e.g., with any one of the sterilizer systems 1 and 100 in FIGS. 1 and 2, respectively). Thus, the steam generator 300 may represent, for example, a detailed example of the steam generator 4 in FIGS. 1 and 2. Moreover, the steam generator 300 of FIG. 4 may be integrated as the steam generator 208 in the steam sterilizer 200 of FIG. 3. The steam generator 300 shown in FIG. 4 includes an inlet 302 to its heat exchanger. Thus, compressed residual steam is received through the inlet 302. The steam generator 300 also includes an outlet 304 from the heat exchanger, through which residual condensate may be discharged. A sensor 306 can be provided to detect the water level in the steam generator so that a control unit (such as control unit 18 previously discussed) can determine when to supply more water to the steam generator 300 through a water supply line 308. The steam generator 300 can also include a pressure transmitter 310 for power / pressure control.

[0056] The present disclosure includes, among other things, a steam sterilizer system for sterilizing articles for medical use, a steam recycling facility, and methods of operating both. Among other things, the present disclosure includes a steam sterilizer system for efficiently recovering the thermal energy of residual steam for use in subsequent steam treatment stages. It should be understood that the various features disclosed herein are contemplated and disclosed in various combinations and subcombinations thereof. [Explanation of symbols]

[0057] 1 Steam Sterilizer System 2. Container 4. Steam generator 6 Sterilizer Chambers 8 Heat exchanger 10. Sewerage System 12 Steam recycling equipment, recycling equipment 14 Compressor 16 First intermediate steam storage unit, intermediate steam storage unit 18 Control Unit 20 Passage 22 Valves 24a, 24b, 24c, 24d Cooling devices 26 Sensing Devices 28 liquid water, water, water volume 30 Entrance 32 screens 34 Steam bubbles 36 Upper steam volume 38 Electric heater 40 Economizer 42 Valves 44 Valve 46 Exit section 48 Passage 50 Drain 52 Valve 54 Bypass Line 56 Branch 58 Valve 60 Branch 62 Valve 100 Steam Sterilizer System 116 Second intermediate steam storage 121 Valve 123 Valve 125 valve 128 Water 132 screens 200 Steam Sterilizer 202 Sterilizer chamber 204 doors 206 Operation Panel 208 Steam Generator 210 Drain 212 Water Tank 214 Header Tank 300 Steam Generator 302 Entrance 304 Exit section 306 Sensor 308 Water supply piping 310 Pressure Transmitter

Claims

1. - a sterilizer chamber configured to receive articles, such as medical supplies, to be sterilized in a sterilization process in the sterilizer chamber; a steam generator configured to receive liquid water and convert the liquid water into steam for delivery to the sterilizer chamber, the steam generator including a heat exchanger; - steam recycling equipment configured to receive at least a portion of residual steam present in the sterilizer chamber after a steam treatment stage of the sterilization process, and configured to pass the residual steam from the sterilizer chamber through the heat exchanger as a heat transfer medium to transfer heat from the residual steam to the liquid water in the steam generator; and Including, The steam sterilizer system, wherein the steam recycling facility includes a compressor configured to receive the residual steam from the sterilizer chamber and compress the received residual steam to a higher pressure, after which the steam recycling facility passes the compressed residual steam to the heat exchanger.

2. 2. The steam sterilizer system of claim 1, wherein the steam recycling facility includes an intermediate steam storage, and the compressed residual steam is guided to the intermediate steam storage before the compressed residual steam is passed to the heat exchanger, and the pressure in the intermediate steam storage is higher than the pressure in the steam generator, and the intermediate steam storage includes, inter alia, a pressure vessel.

3. 3. The steam sterilizer system of claim 2, wherein the intermediate steam reservoir has an inlet at a bottom of the intermediate steam reservoir through which compressed residual steam is received, thereby allowing the residual steam to rise through the water contained within the intermediate steam reservoir.

4. 4. The steam sterilizer system of claim 2 or 3, wherein the intermediate steam reservoir includes a screen with a plurality of holes for diffusing transport of steam bubbles through a water volume in the intermediate steam reservoir, the steam bubbles rising to an upper steam volume above the surface of the water volume.

5. 5. The steam sterilizer system of claim 2, wherein the compressor is positioned in a fluid path between the sterilizer chamber and the intermediate steam storage to compress the residual steam from the sterilizer chamber before it enters the intermediate steam storage.

6. 6. The steam sterilizer system of claim 1, wherein the steam recycling facility includes a cooling device configured to reduce the temperature of superheated residual steam to saturated residual steam, and in particular the cooling device is arranged along the fluid path between the sterilizer chamber and an intermediate steam storage.

7. 7. The steam sterilizer system of claim 6, wherein the cooling device is configured to spray water, in particular to spray water into the compressor.

8. 7. The steam sterilizer system of claim 6, wherein the cooling device is in the form of a heat exchange device provided between the compressor and the intermediate steam store, or in the form of an injector configured to spray water into superheated residual steam upstream or downstream of the compressor.

9. 9. The steam sterilizer system of any one of claims 1 to 8, further comprising a control unit configured to determine that a steam treatment stage of the sterilization process is complete and, based on such determination, control a valve positioned upstream of the compressor to allow residual steam to pass from the sterilizer chamber to the compressor.

10. 10. The steam sterilizer system of claim 1, wherein the intermediate steam storage is a first intermediate steam storage, the steam recycling facility further includes a second intermediate steam storage, and the compressed residual steam is guideable to the second intermediate steam storage before the compressed residual steam is passed to the heat exchanger.

11. The steam sterilizer system of claim 10 when dependent on claim 9, wherein the control unit is configured to operate the steam recycling facility in a first storage operating mode by controlling the compressed residual steam to be provided initially to the first intermediate steam storage until the pressure inside the sterilizer chamber drops below a predefined pressure level.

12. 12. The steam sterilizer system of claim 10 or 11 when dependent on claim 9, wherein the control unit is configured to operate the steam recycling facility in a second storage operating mode by controlling the compressed residual steam to be provided to the second intermediate steam storage instead of the first intermediate steam storage when the pressure inside the sterilizer chamber drops below the predefined pressure level.

13. 13. The steam sterilizer system of claim 9, wherein the control unit is configured to operate the steam recycling equipment in an inter-storage operation mode by controlling the compressed residual steam stored in the second intermediate steam storage unit to be transferred to the first intermediate steam storage unit via the compressor, thereby further increasing the pressure of the residual steam exiting the second intermediate steam storage unit.

14. 14. The steam sterilizer system of claim 12 or 13, wherein the steam recycling facility includes a plurality of controllable valves for controlling the flow of steam to and from the first intermediate steam storage and the second intermediate steam storage, and the control unit is configured to control the controllable valves to switch between the different operating modes.

15. 15. The steam sterilizer system of any one of claims 1 to 14, wherein the steam recycling facility further includes a bypass line extending from a location downstream of the compressor but upstream of the steam generator, the bypass line being selectively controllable to allow compressed residual steam to bypass the steam generator and be returned to the sterilizer chamber.

16. the sterilizer chamber is a first sterilizer chamber, the steam generator is a first steam generator, and the steam sterilizer system comprises: - a second sterilizer chamber configured to receive items, such as medical supplies, to be sterilized; a second steam generator configured to receive liquid water and convert the liquid water into steam for delivery to the second sterilizer chamber, the second steam generator including a heat exchanger; and further comprising 16. The steam sterilizer system of claim 1, wherein the steam recycling facility is also configured to guide the residual steam through the heat exchanger of the second steam generator as a heat transfer medium, so as to transfer heat from the residual steam to the liquid water in the second steam generator.

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